The present invention relates to an electrostatic recording head in which a number of recording electrode styli are arranged in a row and divided into subgroups each including a plurality of styli, and block electrodes are arranged corresponding individually to the subgroups, the styli and the electrodes being combined to effect a matrix connection and drive.
Conventionally known is an electrostatic recording system using an electrostatic recording head. In the recording head, a number of recording electrode styli are arranged in one or more rows, and are divided into subgroups, each including a plurality of styli along a row direction. Block electrodes are arranged corresponding individually to the subgroups. Recording voltages are applied successively to the individual electrode styli and block electrodes of the recording head, thereby forming an electrostatic latent image on a recording medium. Then, the latent image is visualized for information recording.
FIG. 1 illustrates an electrostatic recording system called a flush control system. In FIG. 1, numeral 1 denotes an electrostatic recording head; 2, an electrostatic recording sheet; and 3, a pressure roller. Recording head 1 is constructed so that a plurality of sets or combinations of a number of recording electrode styli 4, arranged in a row, and paired block electrodes 5a and 5b are held insulated from one another by means of insulator 6.
Approximately half of the necessary voltage for each recording cycle is applied to recording electrode styli 4, and the other half is applied to block electrodes 5a and 5b. Recording is executed when the two half voltages are superposed.
FIG. 2 illustrates an electrostatic recording system called a double-sided control system. In FIG. 2, numeral 7 denotes an electrostatic recording head; 2, an electrostatic recording sheet; and 8, a back electrode, In recording head 7, a number of recording electrode styli 9 are held by means of insulator 10. Back electrode 8 is split into a plurality of sections, thus constituting a block electrode. Approximately half of the necessary voltage for each recording cycle is applied to electrode styli 9, and the other half is applied to the block electrode. A method of matrix recording using such a matrix recording head is disclosed in Japanese Patent Publication No. 36-4119, for example.
FIG. 3 shows an arrangement of a prior art matrix electrostatic recording head. In FIG. 3, symbol S designates recording electrode styli, and symbols X1, X2, . . . Xn desginate block electrodes. Symbols A1, B1, A2, and B2 designate element regions of a matrix arrangement including divided sets of electrode styli. Region A1 is situated halfway between block electrodes X1 and X2, extending over both of them. Likewise, region B1 is situated halfway between electrodes X2 and X3, extending over both these electrodes. Regions A1, A2, . . . include n electrode styli each. Corresponding electrode styli of the individual regions are coupled in common to one another, and are connected to their corresponding terminals 1, 2, 3, . . . n of terminal section A. Likewise, regions B1, B2, . . . include m electrode styli each, and corresponding styli of these individual regions are coupled in common to one another, and are connected to terminals 1, 2, 3, . . . m of terminal section B.
In recording, a recording signal voltage is applied to terminal section A or B, and those two block electrodes corresponding to the element region of the matrix to be recorded are selected and supplied with the voltage. In recording element region A4, for example, the voltage or recording signal is applied to block electrodes X7 and X8 and terminal section A. In recording element region B2, moreover, the recording signal is applied to electrodes X4 and X5 and terminal section B.
Usually, wiring board P is used for wiring for the selective supply of the recording signal to the recording electrode styli. A number of wire-bundle junctions C are arranged on the board. Junctions C are connected to connectors CN1 and CN2 by wiring on the board. Conventional driver circuits (not shown) are connected individually to connector pins 1, 2, 3, . . . n.
In the recording head adapted for the matrix drive, as described above, wires W are drawn out from various points, over the whole length of the head in the longitudinal direction thereof or in the arrangement direction of the styli, in order to connect a number of recording electrode styli in common to terminal sections A and B. If the recording head is as long as several tens of inches, and if the electrode styli connected to one of the termianl sections are as many as 100 to 200 in number, the stray capacity and wire-coupling capacity or parastic capacity of the wire bundles increase, thereby causing various troubles. In manufacturing an elongate recording head, these troubles are expressly noticeable.
More specifically, the amount of current necessary for recording increases, for example. Although the current required for the electrostatic recording itself is practically negligible, the driver circuit must be supplied with a large current to charge the stray capacity. Accordingly, driver elements with a large current capacity must be used for the driver circuit, and a high-voltage power source must have a large capacity. When applying a signal to terminal section A, moreover, terminal section B must not be supplied with any voltage. Nevertheless, voltage is supplied also to terminal section B through the wires. While one of the element regions is being recorded, therefore, wrong recording dots will possibly be formed on the adjacent element region.
In order to eliminate such troubles, an arrangement has conventionally been provided in which the stray capacity of the recording dots is reduced. FIG. 4 shows a recording head disclosed in Japanese Patent Publication No. 57-8469, as an example of such a conventional arrangement. In FIG. 4, symbols P1, P2, P3, . . . Pi designate electrode styli, which are arranged in two rows A and B. Symbols E1, E2, . . . En and F1, F2, . . . Fn designate wires; numerals 7 and 8, wiring boards; and symbols Q1, Q2 and Q3 and R1, R3, wiring-board conductor lines. The wires from one row of recording electrode styli are led alternately to the two different wiring boards, and are connected individually to their corresponding conductor lines. In this manner, at least two wiring boards are provided for each row of electrode styli, that is, at least four wiring boards are provided for two stylus rows A and B, and the wires are distributed in a three-dimensional space. Thus, the stray capacity is reduced.
Although the stray capacity can be reduced, in such an arrangement, junctions of wires on the wiring boards are increased in number, thus requiring enlargement of the wiring boards. Moreover, the number of wiring boards is increased, so that the space the boards occupy must also be increased. Accordingly, the manufacture of the recording head is further complicated.